We have developed a pH sensitive sensor for monitoring acidity of an infected wound area, as well as a pH meter for real-time monitoring the pH value. The pH sensor was fabricated by depositing Au and Ag on a PET film using a semiconductor process. The electrodes consist of a working electrode and a reference electrode. Here, the reference electrode was fabricated by synthesizing Polyaniline (PANI) on Ag/AgCl, and the sensor was constructed with four channels in order to measure the pH value in a wide area evenly. Then, the completed system including the pH sensor is 5×5 cm2 in size, and the measured values of pH range from 3 to 9, along with the slope of 50 mV / pH in the overall measurement.